The present invention relates to magnetic resonance imaging, and more particularly to a method suitable for measuring internal distribution of information relating to chemical shift of an organism at a high speed.
As a magnetic resonance spectroscopic imaging for measuring internal distribution of information relating to the chemical shift of an organism at a high speed (hereinafter referred to as MRSI), an EPSM method and a PREP method proposed by Mansfield described in Magnetic Resonance in Medicine, Vol. 1, pp. 370-386 (1984) or the like, and a multiple encoding method proposed by Matsui described in Journal of Magnetic Resonance, Vol. 67, pp. 476-490 (1986) or the like are known. In these methods, a sign of field gradient is reversed periodically, thereby to achieve a high speed using echoes (hereinafter referred to as echo train) generated consecutively, and a measurable spectral bandwidth is determined by an inverse number of the inversion period of the field gradient. In order to widen this spectral bandwidth, a shorter inversion period of the field gradient is required. When the inversion period of the field gradient is simply shortened in order to widen the bandwidth, however, spatial resolution of an obtained chemical shift image is lowered due to a limited switching period of time of the field gradient. In other words, when the spatial resolution of a chemical shift image is improved, a measurable spectral bandwidth is narrowed.